Processes for extraction of nickel with iron-complexing agent

Abstract

The invention provides, in part, a process for extracting nickel from a source material including iron and nickel, by contacting the source material (e.g, an ultramafic ore) with an aqueous ammonia solution containing an iron-complexing agent (e.g., citrate) under suitable conditions, thereby extracting the nickel. The aqueous ammonia solution may optionally contain a sulfur-containing reductant, such as thiosulfate.

1 . A process for extracting nickel from a source material comprising nickel and iron, the process comprising:
 a) providing a source material comprising nickel and iron;   b) providing an aqueous ammonia solution comprising an iron-complexing agent;   c) contacting the source material with the aqueous ammonia solution under suitable conditions, wherein a substantial portion of the iron is solubilized, thereby extracting a sufficient quantity of the nickel from the source material.   
     
     
         2 . The process of  claim 1  wherein the source material comprises one or more of an ultramafic material, an iron-nickel alloy, a nickel sulfide, or an industrial material. 
     
     
         3 . The process of  claim 1  wherein the source material comprises awaruite or josephinite. 
     
     
         4 . The process of  claim 1  wherein the source material comprises serpentinite. 
     
     
         5 . The process of  claim 2  wherein the industrial material is an industrial by-product. 
     
     
         6 . The process of  claim 1  wherein the iron-complexing agent comprises citrate or a salt thereof. 
     
     
         7 . The process of  claim 4 , wherein the citrate is present at a concentration of about 50 mM to about 500 mM. 
     
     
         8 . The process of  claim 1  wherein the iron-complexing agent comprises tartrate, glycolate, oxalate, lactate, or malate, or salts thereof. 
     
     
         9 . The process of  claim 1  wherein the iron-complexing agent is capable of solubilizing a substantial portion of the iron present in the source material. 
     
     
         10 . The process of  claim 1  wherein the iron-complexing agent is capable of complexing a substantial portion of the iron present in the source material. 
     
     
         11 . The process of  claim 1  wherein the process further comprises a sulfur-containing reductant. 
     
     
         12 . The process of  claim 11  wherein the sulfur-containing reductant is thiosulfate. 
     
     
         13 . The process of  claim 12  wherein the thiosulfate is present at a concentration of about 2 mM to about 50 mM. 
     
     
         14 . The process of  claim 1  wherein the suitable conditions comprise a pH that is weakly alkaline. 
     
     
         15 . The process of  claim 14  wherein the pH ranges from about 7.5 to about 8.5. 
     
     
         16 . The process of  claim 1  wherein the suitable conditions comprise a temperature ranging from about 20° C. to about 90° C. 
     
     
         17 . The process of  claim 1  wherein the process is carried out at atmospheric pressure. 
     
     
         18 . The process of  claim 1  wherein the source material is milled to a suitable particle size. 
     
     
         19 . The process of  claim 1  further comprising precipitating a leachate comprising the iron and the nickel.